The invention relates to a semiconductor device comprising a substrate which comprises silicon, with a layer thereon comprising at least organic material, in which layer a passage is present to the substrate having walls transverse to said layer, while a metal layer is present on at least that portion of the substrate which adjoins said passage, the organic material which forms the walls of the passage being covered by an oxide liner, and a metal being present in said passage.
The invention also relates to a method of manufacturing a semiconductor device, comprising the following steps:
a metal layer is provided on a substrate comprising silicon,
a layer comprising at least an organic material is provided on the metal layer,
a passage is formed in the layer of organic material,
an oxide liner is deposited by means of a CVD process on the organic material which forms the walls of the passage which are transverse to the substrate, and
the passage in the organic material is filled with a metal.
Such a device is known from JP-A-10 284 600. In the known device, a layer of organic material is provided on a substrate, in which layer a contact opening and an interconnection groove are provided (xe2x80x9cdual damascene structurexe2x80x9d) by the so-called dual damascene method, which opening and groove are filled with a conductive interconnect material such as Al or Cu. An inorganic protective layer is provided on the walls of organic material of both the contact opening and the interconnection groove. The material of which the protective layer consists is, for example, SiO2. This layer is necessary for preventing the metal from penetrating and damaging the organic material during the deposition in the damascene structure (metallization).
It was found, for example with the use of a damascene structure filled with Cu, that this Cu diffuses into the organic material in the course of time. If Al is used as the interconnect material, the problem arises that the Al reacts with the protective layer, so that it is not very well possible to obtain a uniform filling of the interconnection groove and the contact opening.
The invention has for its object to provide a device of the kind described in the opening paragraph wherein an improved barrier is present between the organic material and the interconnect metal, while at the same time the organic material is protected during the various process steps.
The device according to the invention is for this purpose characterized in that a metal liner comprising Ti or Ta is present between the oxide liner and the metal present in the passage.
The metal liner comprising Ti or Ta prevents the conductive interconnect material with which the damascene structure is filled from diffusing into the organic material. In the case of a Cu metallization, a Ta liner, which serves as a barrier, in particular also ensures a good adhesion of the Cu in the damascene structure. If Al is used as the interconnect material, the metal liner ensures that the damascene structure can be uniformly filled with Al without adverse reactions occurring at the walls of the contact opening and the interconnection groove.
It is noted that the provision of a metal liner comprising Ti or Ta on the walls of the contact opening and the interconnection groove is known per se from U.S. Pat. No. 5,904,565. The object of the method described in this document, however, is to achieve an optimized conduction between the Cu and a subjacent metal surface. There is no question of an organic layer which is to be protected. The combination of a conductive barrier with an oxide liner is not disclosed or even suggested.
An additional advantage is that no pollution of the metal liner comprising Ti or Ta takes place in the device according to the invention. If this liner is directly applied on the organic material, a reaction will occur and the metal liner will be polluted by organic material, with the result that it will have a higher resistance. The deposition of an oxide liner between the metal liner and the organic material solves this problem. The oxide liner also provides a good protection for the organic material during cleaning of the contact surface with the subjacent metal by means of a sputtering etching treatment. This sputtering etching treatment is carried out before the metal liner comprising Ti or Ta is provided.
The method according to the invention is characterized in that the oxide liner is provided by means of low-temperature CVD, and in that a metal liner comprising Ti or Ta is provided on the oxide liner after the provision of this oxide liner.
In JP-A-10 284 600, the oxide liner is provided by means of plasma CVD (Chemical Vapor Deposition, known to those skilled in the art). The use of low-temperature CVD, however, renders it possible to ensure that the thickness of the oxide liner is the same in all locations. This is not possible with the use of plasma CVD.